Watertight bulkhead doors are well known on naval vessels. As used herein, “bulkhead door” should be taken to mean a sealable door installed in a vertical surface (bulkhead door), a horizontal surface (“hatch cover”), or a door-within-a-door (“scuttle”). A typical prior art bulkhead door includes a resilient gasket that mates with an edge of a collar surrounding a bulkhead opening and extending from the bulkhead outer surface. A plurality of pivotable latches, known in the art as “dogs”, are mounted on the bulkhead and may be pivoted into position against the outer surface of the door where they progressively engage wedged areas, known in the art as “strikers”. Such progressive rotational engagement causes the gasket to be compressed against the collar, sealing the bulkhead opening against water and/or gas transmission.
In some prior art embodiments, the dog spindles extend pivotably through the bulkhead and are mechanically linked around the interior of the bulkhead opening such that actuation of a master handle, extending pivotably through the bulkhead and actuable from either side thereof, causes all the dogs to be engaged or disengaged synchronously.
Prior art bulkhead door systems employing exposed metal dogs create an undesirably enhanced radar cross-section, to the benefit of an enemy combatant in naval warfare.
Further, prior art doors typically are formed by stamping from sheet metal and include a stamped relief pattern to enhance flexural rigidity. It has been found that such a pattern is highly undesirable, for two reasons: first, the pattern greatly increases radar reflection from the door; and second, the pattern is difficult to wash down easily and thoroughly as may be required for washdown of a chemical spill or biochemical attack. For these considerations, a smooth surface is preferred.
The gasket of a prior art door system is relatively exposed to damage by fire on the exterior of the bulkhead, resulting in failure of the watertight and gastight seal.
Use of a plurality of spaced-apart dogs results in inconsistent lockdown pressure across the door such that under extreme pressure conditions the door may become distorted and leakage may occur between adjacent dog positions, especially when the door is formed of a non-metal polymeric composite.
What is needed in the art is an improved latching system for a bulkhead door that eliminates exposed metal dogs on the exterior of the door, provides consistent lockdown pressure across the door, permits easy and thorough washdown from a chemical spill or biological attack, and shields the door gasket from attack by fire.
It is a principal object of the present invention to provide a uniform lockdown pressure at all points of a bulkhead door gasket.
It is a further object of the invention to reduce the radar cross-section of a bulkhead door assembly.
It is a still further object of the invention to protect a bulkhead door gasket from exposure to fire.
It is a still further object of the invention to facilitate easy, rapid, and thorough cleanup of a chemical spill or a biological attack.
It is a still further object of the invention to utilize existing bulkhead openings and door actuation mechanisms.